Comparative effectiveness of cervical vs thoracic spinal-thrust manipulation for care of cervicogenic headache: A randomized controlled trial

Background There is ample evidence supporting the use of different manipulative therapy techniques for Cervicogenic Headache (CgH). However, no technique can be singled as the best available treatment for patients with CgH. Therefore, the objective of the study is to find and compare the clinical effects of cervical spine over thoracic spine manipulation and conventional physiotherapy in patients with CgH. Design, setting, and participants It is a prospective, randomized controlled study conducted between July 2020 and January 2023 at the University hospital. N = 96 eligible patients with CgH were selected based on selection criteria and they were divided into cervical spine manipulation (CSM; n = 32), thoracic spine manipulation (TSM; n = 32) and conventional physiotherapy (CPT; n = 32) groups, and received the respective treatment for four weeks. Primary (CgH frequency) and secondary CgH pain intensity, CgH disability, neck pain frequency, neck pain intensity, neck pain threshold, cervical flexion rotation test (CFRT), neck disability index (NDI) and quality of life (QoL) scores were measured. The effects of treatment at various intervals were analyzed using a 3 × 4 linear mixed model analysis (LMM), with treatment group (cervical spine manipulation, thoracic spine manipulation, and conventional physiotherapy) and time intervals (baseline, 4 weeks, 8 weeks, and 6 months), and the statistical significance level was set at P < 0.05. Results The reports of the CSM, TSM and CPT groups were compared between the groups. Four weeks following treatment CSM group showed more significant changes in primary (CgH frequency) and secondary (CgH pain intensity, CgH disability, neck pain frequency, pain intensity, pain threshold, CFRT, NDI and QoL) than the TSM and CPT groups (p = 0.001). The same gradual improvement was seen in the CSM group when compared to TSM and CPT groups (p = 0.001) in the above variables at 8 weeks and 6 months follow-up. Conclusion The reports of the current randomized clinical study found that CSM resulted in significantly better improvements in pain parameters (intensity, frequency and threshold) functional disability and quality of life in patients with CgH than thoracic spine manipulation and conventional physiotherapy. Trial registration Clinical trial registration: CTRI/2020/06/026092 trial was registered prospectively on 24/06/2020.

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INTRODUCTION
Globally, headache disorders affect approximately 66% of the population between the ages of 18 and 65 years at least once a year.66% of men and 57% of women report headache once in their lifetime which reduces the quality of life, work productivity and costs to society. 1 Cervicogenic headache (CgH) is a distinct form of headache and accounts for 17.8% of all headaches and the prevalence rate is between 0.4% and 20%.The prevalence rate of CgH is 0.21% in females and 0.13% in males and has various causative factors. 2 It has a significant negative socioeconomic impact and is a burden on the community and public health.The cause of the headache is located in the neck region and the pain is made worse by movements of the head and neck. 3The most accepted mechanism of CgH is found between the trigeminal nerve and C1 -C3 nerves in the trigemino-cervical nucleus. 4It usually arises from musculoskeletal structures such as the cervical vertebra, intervertebral disc, or paravertebral muscles.The clinical features of CgH include unilateral headache, limited range of motion (ROM) at the neck, and radiating pain to the head or face region. 5nerally, CgH is diagnosed on the bases of a detailed history and clinical assessment. 6ysical examinations typically reveal pain in the cervical regionneck pain (NP), decreased neck movements, upper quarter muscle tightness and loss of muscle characteristics. 7The flexion rotation test (FRT) is a valid, reliable and accurate method for assessing cervical ROM, it is recognized as the diagnostic tool for CgH. 8 The management of CgH consists of pharmacological and non-pharmacological methods, in which the pharmacological means are associated with many side effects. 9There are many non-pharmacological treatment modalities available such as; physical modalities, positional therapy, muscle strengthening exercises, ergonomic guidance and patient education etc. 10 It has been estimated that 34% of US citizens receive some sort of physiotherapy for CgH each year. 11 physiotherapy, joint mobilization and manipulation are the most commonly used treatment modality for treating CgH patients. 12The two types of manipulation techniques used in CgH are cervical spine manipulation (CSM) and thoracic spine manipulation (TSM) and both of these techniques use high velocity, low amplitude thrusts (HVLAT).Some studies looked solely at the effects of manipulating the cervical spine in cases of Cervicogenic headache. 5,13,14McDevitt AW et al. found that thoracic spine manipulation alone significantly improved neck-related disability in CgH, but had no effect on headache-related disability but participants reported overall improvement of their condition. 15Dunning JR et al. looked into the mixed effects of cervical and thoracic spine manipulation in CgH patients at the same time and found clinically better effects in pain parameters and functional disability at 3 months follow-up. 16However, studies have shown that treating Cervicogenic headache with combined spinal manipulation (cervical and thoracic) or just the cervical spine or thoracic spine alone is effective.However, so far no studies have compared and investigated the individual effects of cervical spine manipulation, thoracic spine manipulation and conventional physiotherapy for treating CgH patients.
4][15][16] However there are no specific treatment protocol in relation to the type of manipulation technique that is most efficient.Nevertheless, there is a scarcity of evidence in comparing the individual effects of cervical and thoracic manipulation approaches in Cervicogenic headache, particularly regarding its clinical and functional aspects.
Additionally, no studies have attempted to address the shortcomings and gaps observed in the existing literature on the management of CgH, such as a lack of comparison between manipulative therapy techniques, poor trial designs and quality and small sample sizes.
Therefore, our study objective was to compare and investigate the pragmatic effects of cervical and thoracic manipulation techniques on patients with Cervicogenic headache.This randomized clinical trial hypothesized that there is a difference in primary and secondary outcome measures between cervical spine manipulation, thoracic spine manipulation, and conventional physiotherapy for the treatment of CgH patients.

Study design
The trial was a parallel-group, prospective, single-blinded, randomized controlled trial.
The required participants were screened by a physician at the University hospital between 1 st July 2020 and 31 st July 2022 in accordance with the Cervicogenic headache diagnostic criteria 11.2.1 from the ICHD-3 (International Classification of Headache Disorders). 17Ninety-six (N=96) participants who fulfilled the eligibility criteria were randomly allocated into three groups equally: the cervical spine manipulation (CSM; n=32), thoracic spine manipulation (TSM; n=32), and conventional physiotherapy (CPT; n=32) groups through a computergenerated simple random table and the allocation of the participants to each group was concealed using sealed envelopes.The computer did not generate the group until it was time to randomize each participant, ensuring that the allocation was concealed.No significant changes were made while the study was being carried out because it was designed as a followup to a pilot study and the 6-month follow-up data collection was completed on 31 st January 2023.
The research was conducted at #####, and the Department Ethical Committee (DEC) granted ethical approval under the reference number RHPT/019/042.The DEC accepted the study protocol as well as the informed consent forms.The study involved human participants which followed the instructions outlined in the Declaration of Helsinki (1964) and prospectively registered in clinical trial.gov.inCTRI/2020/06/026092 on June 24, 2020.

Participants
Patients aged between 18-60 years, suffering from CgH (>3 months) were screened to include in the study.They were diagnosed based on the diagnostic criteria developed by the Cervicogenic Headache International Study Group (CHISG) by an orthopedic surgeon with twenty years of clinical experience in diagnosing and treating the CgH and it falls under the International classification of disease -10 (ICD-10) code of G44.841. 6Patients with pain intensity ≥3 on a numerical pain rating scale (NPRS), CgH resulting from pain in the neck followed by headache, limited neck movements and neck stiffness and cervical spine disorders were allowed to participate in the study.Other primary headaches such as migraine and tensiontype headaches (TTH), whiplash injuries, participants who show signs of the five 'D's' (dizziness, drop attacks, dysarthria, dysphagia, diplopia) or who have signs of the three 'N's (nystagmus, nausea, other neurological symptoms (cord compression or nerve root involvement), contraindications to manipulative therapy (tumour, degenerative and inflammatory arthritis, osteoporosis, dislocation, fractures, and steroid intake), underwent previous head and neck surgeries, had physiotherapy or other complementary therapies in the last three months were excluded.The flow of the study program was documented following the CONSORT guidelines and displayed in (fig.1).
The list of participants was compiled from the #####, and requests were sent to the participants via personal e-mail.Two orthopaedic surgeons with ten to fifteen years of experience diagnosed the CgH patients after they consented to participate in the study.The research was carried out at the Department of Physical Therapy and Health Rehabilitation, #####, using the recommended study protocols.

Interventions
Certified physiotherapists having 10 -15 years of experience in spinal manipulation for CgH provided the approved technique in each group.All the participants in the three groups had given their willingness to participate in the study after getting detailed information about the study protocol.The treatment consisted of a 10-minute hydro collator pack application to relax the muscles of the area around the neck and upper back.Following this, the participant's neck muscles and joints were assessed for any musculoskeletal dysfunction.After that, the participants were given the manipulation techniques as per the directions of the study protocol.
Standardized treatment techniques were used for all the group participants to reduce intervention bias.The procedures of intervention and follow-up measurements were recorded in standardized forms.During the study period, the participants were asked to refrain from taking any other type of intervention, they received the concerned interventions 3 times per week for 4 weeks.

Spinal manipulation therapy
Peterson and Bergman defined SMT as a high-velocity low-amplitude thrust (HVLAT) technique.Four experienced physiotherapists having experience in SMT performed this technique after evaluation of each participant by physical examination and palpation.The therapist located the sites of abnormal changes in each vertebra and then manipulated the area following the study's recommendations.If any participant reported any new red flag signs or showed no signs for manipulation, such as no pain or musculoskeletal dysfunction, then the procedure was not performed.

Cervical spine manipulation (CSM)
To perform the C1-C2 cervical spine manipulation (CSM) the participant was instructed to lie down in a face-up position with upper and lower extremities kept aside relaxed.The head was kept in a neutral position and the treating therapist stands at the patient's head side and holds the chin of the patient with the right side hand.The therapist left hand holds the posterior aspect of the head and does two to three free rotatory movements.Afterwards, the therapist did HVLAT technique in either the right or left direction based upon the symptoms informed by the patient (fig.2).The manipulation was done first on the pain-free side and then on the painful side and the rotation range is limited by the target vertebra. 18

Thoracic spine manipulation (TSM)
To perform the T1-T2 thoracic spine manipulation (TSM) the patient lays down in a face-up position with his arms crossed across his chest in a vertical direction, with elbows in the top position.The therapist stands beside the participant and faces towards the him.The treating therapist's left hand held the patient's both elbows together to apply downward force, while the right hand was kept under the spinous process of the target vertebra's lower vertebra with the thenar eminence and middle phalanx of the middle finger.The vertical downward thrust (anterior to posterior) was applied to the target vertebra by the therapist's left hand, and the thrust was adjusted by the right hand through pronation and radial deviation.Manipulation was performed by lowering the knees to generate thrust force while keeping the therapist's spine straight and head up (fig.3). 15

Conventional physiotherapy (CPT)
The participants of the CPT group received massage therapy for 15 minutes using Queen Helene, Cocoa Butter face & body cream, New York, USA.The patient lays down in a face-up position, with the posterior aspect of the head resting on a folded towel.The treating therapist stands by the patient's head side and uses the tips of the middle fingers of both hands to perform circular kneading on both sides of the C1 to C7 vertebra.This maneuver was repeated 3 times for each cervical vertebra, beginning from the C7 vertebra and working towards the C1 vertebra.The neck was then turned to the other side, and the same manoeuvre was repeated from insertion to origin on the sub-occipital and paravertebral muscles. 19rticipants of all three groups were asked to perform neck isometric exercises three times per day, every day.The patient was asked to keep his hand over his forehead and resist the forward movement of his neck for 10 seconds and the same movement was repeated 15 times.Similarly, the patient was asked to keep the hand on the posterior and lateral sides of the head, and resist the backward and sideways movements of the neck.Also, static active stretching exercises for the upper trapezius, levator scapulae, scalene, and sternocleidomastoid muscles were taught to the patients, which was maintained for the 30s with 3 repetitions.The patients were instructed to keep doing this set of exercises after 4 weeks of various intervention protocols and they were asked to maintain an exercise log book to check the treatment compliance.

Outcomes
All the outcome measures were recorded by a blinded physiotherapist, and the scores were entered in a data sheet.The scores were measured at the beginning of the study, after 4weeks, 8-weeks, and at 6-months.

Primary outcome
CgH frequency: It is a self-administered outcome variable where the patient enters his CgH pain experience in a medical log book every evening to find the number of painful days in 4weeks. 20

Secondary outcome
CgH pain intensity: The pain intensity of CgH was assessed using an 11-point numerical pain rating scale (NPRS).Patients rated their typical level of pain status during the previous week on a 10 cm horizontal line, with one end 0 representing "no pain" and the other end 10 representing "worst pain imaginable." 21H disability: The Headache Impact Test (HIT) questionnaire is a valid and reliable instrument to assess the level of disability in CgH patients.It consists of six items: pain, social functioning, role functioning, vitality, cognitive functioning, and psychological distress.The score categories are no or mild disability (49 or less), moderate disability (50-55), severe disability (56-59), and complete disability (60-78).22 NP frequency: It is a self-administered outcome variable where the patient enters his neck pain experience in a medical log book every evening to find the number of painful days in 4-weeks.20 NP intensity: The pain intensity of neck pain was assessed using an 11-point numerical pain rating scale (NPRS).Patients rated their average pain intensity over the past week on a 10 cm horizontal line, with one end 0 representing "no pain" and the other end 10 representing "worst pain imaginable."21 NP pressure threshold: It is the lowest intensity at which a given stimulus is perceived as painful and it was measured using an instrument Algometer (Baseline, 22-pound dolorimeter, ID, USA).The tip was placed over the fixed points on the back of the neck and assessed through palpation.It is a reliable and valid tool for determining pain threshold.23

Cervical flexion-rotation test (FRT):
The cervical flexion-rotation test is done with the patient in a supine lying position.The therapist passively maintains the patient's neck into full flexion to relax the structures of the middle and lower cervical spine, then the patient's head is passively rotated in each direction while the flexed position is maintained and the range of motion is measured. 8ck disability index (NDI): It is a reliable and valid self-reported questionnaire with ten items scored on a 0 to 5 scale.The grades of disability are determined based on the scores obtained, which are as follows: 10-29% mild; 30-49% moderate; 50-69% severe; 70% or more is a complete disability. 24ality of life: The EQ-5D (Euro Qol 5D) is self-administered health related quality of life (HRQOL) questionnaire, which measures the five dimensions of quality of life.It includes mobility, self-care, usual activities, pain/discomfort, and anxiety/depression.It is used to assess the CgH patients' overall quality of life with a scale of 0 (worst) to 100 (best). 25

Sample size
For calculating the number of subjects to be include in the study, the primary outcome measure CgH frequency in days was taken into consideration based on previous pilot study which found the effect of spinal manipulation in the treatment of CgH, with 10 subjects in each group.Using the G-Power software (version 3.1.9.2; Franz Faul, University of Kiel, Germany), assuming a two-sided α = 0.05, and power (1-β = 0.80), to detect an effect size of 1.2 CgH days and mean difference of 4 CgH days (between groups) and a standard deviation of 0.5, an approximately 28 samples were required.In assuming 10% dropout, we enrolled 32 subjects in each group.

Blinding
Because of the experimental nature of the study methodology, it was not feasible to blind the treating therapist as well as the participants of the study.The therapists who assessed the outcome variables at baseline, 4-weeks, 8-weeks, and 6-months were blinded.Therefore, the therapist providing the treatment and the therapist measuring the data were different individuals.In addition, the outcome-measuring therapist continued to be masked to the participant's groups at all-time intervals.Also, participants were asked not to discuss their treatment details with their peers or the outcome-measuring therapist.In addition, authors did not have access to information that could identify individual participants during or after data collection.

Statistical methods
The normality of study participants' demographic characteristics was analyzed through the Kolmogorov-Smirnov test.The outcome data were presented in the form of a mean and standard deviation with a 95% confidence interval.The effects of treatment at different time intervals were analyzed using a 3 × 4 linear mixed model analysis (LMM), with treatment groups (cervical spine manipulation, thoracic spine manipulation, and conventional physical therapy) and time intervals (baseline, four weeks, eight weeks, and at six months) and a statistical significance level of α=0.05.All the statistical tests were done using GraphPad-Prism (version 9.1), Boston, MA, USA.

Participants
Out of the 130 participants screened, eight had a VAS score greater than 8, ten participants were having some sort of orthopaedic injuries, four participants were undergone joint surgeries, and twelve refused to involve in the research and were excluded.N=96 participants were chosen based on the eligibility criteria and allocated to one of the three groups.Two participants in the CSM and CMT groups, and three in the TSM group, did not complete the 4-week treatment program with a 6-month follow-up (fig.1), and the study analysis assumed the intention to treat principle method.Compliance with follow-up data collection at 6 months was 93%, adherence to study protocols (e.g., number of visits) was 100%, and none of the participants in the three groups received any additional care that was not included in the three study interventions.At baseline, the demographic characters such as age (years), height (cm), weight (kg), and BMI (kg/m 2 ) scores did not report statistically significant variation between the groups (p>0.05).In all three groups, females (53-56%) are affected more than males.At baseline, the clinical variables also did not show any significant difference between groups (p0.05).The clinical presentation of headache is more unilateral (78% -84%) than bilateral, and the majority of CGH cases have associated neck pain (84% -88%).(Table 1).

Primary outcome
The preliminary score on the primary outcome CgH frequency score among the CSM, TSM, and CPT groups showed no statistical variation (p≥0.05) which indicated the homogenous presence of study participants.The mean and standard deviation (SD) of the CgH frequency score between the three groups, at four-time periods, was shown in  4).The complete interpretation shows a slight leaning towards the CSM group than TSM and CPT group in CgH frequency.

Secondary outcomes
The preliminary score on the secondary outcome variables between the CSM, TSM, and CPT groups showed no statistical variation (p≥0.05) which indicated the homogenous presence of study participants.The mean and standard deviation (SD) of the secondary outcomes between the three groups, at four-time periods, was shown in  4).The complete interpretation shows a slight leaning towards the CSM group than TSM and CPT group in all the secondary variables.

DISCUSSION
Despite having manual therapy reference in clinical practice guidelines (CPG) recommended by Ontario protocol for traffic injury management (OPTIMa) for the use of cervical and thoracic spine for patients with CgH, so far no randomized clinical trials (RCT) have been conducted to find the individual effects of CSM, TSM and conventional physiotherapy for CgH patients. 26Based on our information, this is the first RCT conducted to investigate and compare the individual effects of cervical and thoracic spine manipulation, with conventional physiotherapy in CgH patients with 6-month follow-up period.The recent report shows that the lower cervical spine (C5, C6, and C7) and upper thoracic spine (T1 and T2) are known to be a more mobile and functional region in the human body, where stability is sacrificed and more prone to joint pathologies like spondylosis, spondylolisthesis, disc degeneration, disc bulge and herniation.Patients with such joint dysfunctions may experience unilateral or bilateral CgH, diffuse pain in the neck region, restricted neck movements, and disturbed activities of daily living (ADL). 27cording to this study, after four weeks of intervention the cervical spine manipulation (CSM) group showed statistically significant changes in all the outcome measures in CgH patients.When compared to TSM and conventional physical therapy, CSM is more effective in managing CgH pain (MCID = 0.9, 9%) and associated neck pain (MCID = 1.3, 13%) at 6 months.CgH and neck pain frequency was also significantly lower in the CSM group (MCID = 3.2, 11%; 4.8, 16%) than in the TSM group, which was supported by Dunning JR et al. 16 So far, no studies have looked at the changes in CgH disability and neck disability, but this study looked at the benefits of cervical spine manipulation (MCID = 8.3, 20%; 12.28, 25%) over thoracic spine manipulation.However, these findings were contradicted by Borusiak et al.
findings. 28According to our findings, HVLAT technique in a cervical vertebra of a short duration (less than 2 ms) promotes afferent nerve fibre activity via joint receptors.It improves the overall action and properties of the neck muscles by activating the alpha motor neuron. 29It alters the sensory fiber activity by activating the joint receptors, thereby changing the α-motor neuron activity levels and subsequent muscle reaction.Because of the high mobility of the cervical spine, CSM can stimulate the receptors of deep neck muscles and sub-occipital muscles, which TSM is not able to do. 30Other theories for the pain-modulating effects of cervical manipulation included biomechanical, vertebral (temporal summation), and neural (central descending pain inhibitory pathway) mechanisms which were noted by Bialosky JE et al and Haavik-Taylor H et al. 5,31,32 Our findings also showed that thoracic spine manipulation improved both primary and secondary outcomes in CgH patients.TSM was also helpful in improving the pain parameters, functional disability and quality of life significantly.It was agreed by research by McDevitt AW et al 15 and suggests that TSM speeds up the healing process.Although several types of research have been conducted to find the effects of different types of spinal manipulation, the real mechanical and neuro-physiological alterations behind these changes have not yet been found and are unclear, but Bialosky et al. suggest that the effects may be due to potential neurophysiological and biomechanical effects, as well as possibly placebo effect. 31According to Masaracchio M et al, TSM, impedes the excitation of pain-stimulating nerve fibres in the apophyseal joints, intervertebral discs, paraspinal muscles and ligaments, resulting in pain reduction and improved joint range of motion in mechanical neck pain.The same neurophysiological changes would have a minor impact on sensory receptors, which relaxes the paraspinal muscles and decreases the pain status in CgH patients. 33The little changes in the conventional physical therapy group on pain intensity and other outcome variables explained the analgesic effect of CPT on cervicogenic headache.It promotes the anti-nociceptive response by activating the opioid and oxytocin interaction through the release of neurotransmitters by stimulating the local nerves.Application of massage on the trigeminalcervical area reduces inflammatory responses, reduces neural sensitivity and plays a significant function in decreasing the tension of the sub-occipital and para-vertebral cervical spine muscles, which is another important mechanism of physical therapy on CgH patients. 34,35The findings of this trial would assist physiotherapists in making decisions to select the best manual therapy approach for CgH patients.

Limitations
The study had some limitations during its execution, which should be considered for future studies.First, the study included both genders, but the reports collected were not calculated independently during the statistical analysis, these differences may influence the research reports.Second, it is impossible to ensure that the subjects completed the questionnaires daily rather than after a week or four weeks.Third, this study lacks a placebo group to determine the true effects of treatment groups.The beneficial effects of various manipulation techniques on pain and other symptoms in Cervicogenic headache were investigated.Finally, the treatment preference of physiotherapists and patients was not asked which could have affected the results.
Future studies are recommended to find the biomechanical and biochemical mechanisms underlying the clinical and functional changes of these manipulation techniques in treating patients with CgH symptoms.

CONCLUSION
The reports of this current randomized clinical study found that cervical spine manipulation experienced significantly better improvements in pain parameters (intensity, frequency and threshold) functional disability and quality of life in CgH than thoracic spine manipulation and conventional physiotherapy.The report also provided strong evidence in the field of manual therapy for cervicogenic headache, a common and costly clinical condition.
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Figure legends : Figure 1 :
Figure legends: Figure 1: Flow chart showing the study details.

Figure 2 :
Figure 2: Figure showing the cervical spine manipulation.

Figure 3 :
Figure 3: Figure showing the thoracic spine manipulation.

Figure 4 :
Figure 4: Pre and post outcome measures of CSM, TSM and CPT groups.

Table 2
and at 6-months' measurement.The post-hoc Bonferroni analysis and the standard mean difference showed more percentage of improvement in CgH pain frequency in the CSM group than TSM and CPT groups (fig.

Table 2 :
Pre and post mean and SD of outcome measures of CSM, TSM and CPT groups.

Table 3 :
Pre and post mean difference and confidence interval (upper limit and lower limit) scores of CSM, TSM and CPT groups.Cervical spine manipulation, TSM -Thoracic spine manipulation, CPT-Conventional physiotherapy, CgH -Cervicogenic Headache